This invention relates to an improved watercraft speed measuring arrangement employable with a watercraft propulsion unit. Specifically, the invention provides a vessel speed measuring system which will not be rendered inoperable or inaccurate in its performance if the associated propulsion unit strikes a piece of debris (e.g., driftwood, or the like) during operation of the watercraft upon a body of water.
It has been known to employ display meters in connection with water vessels in order to communicate various operational data to an operator. Such various meters might include a speedometer, a clock or timer, and or a trip meter or odometer. It has been the common practice to employ some type of sensing device from which each meter receives the operational data which it then conveys in an appropriate manner to an operator. The sensing devices are oftentimes positioned remotely from their respective display meters. The display meters are positioned so that they may be readily observed by an operator. A suitable communication line relays the sensed data at each sensor to its respective meter so that the particular operational data can be displayed in an appropriate manner.
Since the present invention involves a speed indicating device, an example of a known prior speed indicating arrangement will now be described. It has been known to provide a Pitot tube (i.e., a device used to measure the total pressure of a fluid stream) within a port located within a lower outboard portion of a watercraft propulsion unit. The lower outboard portion is usually streamlined in horizontal cross-section (e.g., teardrop-shaped) and has a generally vertically disposed forward region which basically forms a straight line along its vertical length. In an effort to accurately sense the pressure at such a structure, the port has been arranged so that it opens forwardly (i.e., in the advancing direction of an associated watercraft) within the leading edge of the lower outboard portion, and so that it is positioned beneath the hull of the watercraft, in order that movement of the watercraft across a body of water will cause the Pitot tube to encounter a pressure force as water impinges upon it. This pressure force is subsequently transmitted to a pressure detector which is built into the speedometer. Such transmission may occur through any suitable conduit system communicating the port opening to the pressure detector of the speedometer. The pressure detector measures the pressure force and converts it into a quantity representative of the vessel speed, which quantity is then shown upon the display of the speedometer in any suitable fashion (e.g., as digital numerical figure or by a pivotal needle situated upon a calibrated background or scale).
The above-described known vessel speed detecting arrangement has proved to be quite satisfactory in providing an operator with vessel speed information under many operational circumstances. However, floating, or somewhat submerged, debris (e.g., driftwood, or the like) can cause the known arrangement to malfunction so that it cannot provide a reliable and accurate measurement or, under certain circumstances, render it totally inoperative. Specifically, problems can arise with such an arrangement when debris hits upon the lower outboard portion of the propulsion unit during navigation. In some instances, the debris may forcefully contact the pressure intake port, and a piece of the debris may enter the port and become inadvertently lodged therein. Consequently, under such circumstances, the pressure intake port will not be able to incur, and relay, the total pressure value which it would otherwise be subjected to during operation, as the lodged debris may block, in whole or in part, the port. Thus, the speedometer will show a lower speed value than the actual speed value of the vessel, or possibly no speed value at all.
While such a problem may be overcome by having an operator physically remove the lodged debris from within the pressure intake port, such removal can be difficult, for obvious reasons (especially if the operator attempts to perform such a task by leaning overboard and reaching to the pressure intake port).
Therefore, it is a principal object of the present invention to provide an improved vessel speed measuring system for a marine propulsion arrangement.
It is additionally an object of the invention to provide a vessel speed measuring and indicating system, having a pressure intake port within a leading edge of a lower outboard portion of the propulsion arrangement, which is structured to prevent debris, such as driftwood or the like, from entering and becoming lodged within the pressure intake port during operation of the vessel, so that the vessel speed can be accurately measured and displayed.